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std::mask_array(3) C++ Standard Libary std::mask_array(3) NAME std::mask_array - std::mask_array Synopsis Defined in header <valarray> template< class T > class mask_array; std::mask_array is a helper template used by the valarray subscript operator with std::valarray<bool> argument. It has reference semantics and pro- vides access to the subset of the valarray consisting of the elements whose indices cor- respond to true values in the std::valarray<bool> mask. Member types Type Definition value_type T Member functions constructor constructs a mask_array (public member function) destructor destroys a mask_array (public member function) operator= assigns contents (public member function) operator+= operator-= operator*= operator/= operator%= performs arithmetic operation on the array referred by mask. operator&= (public member function) operator|= operator^= operator<<= operator>>= Example // Run this code #include <iostream> #include <valarray> int main() { std::valarray<int> data = {0,1,2,3,4,5,6,7,8,9}; std::cout << "Initial valarray: "; for(int n: data) std::cout << n << ' '; std::cout << '\n'; data[data > 5] = -1; // the type of data>5 is std::valarray<bool> // the type of data[data>5] is std::mask_array<int> std::cout << "After v[v>5]=-1: "; for(int n: data) std::cout << n << ' '; std::cout << '\n'; } Output: Initial valarray: 0 1 2 3 4 5 6 7 8 9 After v[v>5]=-1: 0 1 2 3 4 5 -1 -1 -1 -1 http://cppreference.com 2022.07.31 std::mask_array(3)
NAME | Synopsis | Member types | Member functions | Example | Output:
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